Scale



F. M. STEVENS'.

SCALE. APPLICATION FILED rss. 2, 191s.

IENEVED FEB. 18. 1920.

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Patented Aug. 31, 1920.

F. M. STEVNS.,

SCALE.

APPLICATION FILED FEB. 2, i916. nsnEwEn Fis. 18. 1920.

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UNITED STATES PATENT OFFICE.

FREDERICK M. STEVENS, OF NEW YORK, N. Y., ASSIGNOR TO JOHN CHATILLON & SONS,

A CORPORATION OF NEW YORK.

SCALE.

specification of Letters Patent.

Patented Aug. 31, 1920.

Application led February 2, 1916. Serial No. 75,630. Renewed February 18, 1920. Serial No. 359,538.

T0 all whom it may concern Be it known that I, FREDERICK M. STE- VENS, a citizen of the United States, residing at New York, in the county ofV New York and State of New York, have invented certain new and useful Improvements in Scales, of which the following is a full, clear, and exact specification.

This invention relates to scales and has particular reference to what are known as trip scales, which consist of a base carrying a balanced frame, and the frame carrying a pan on each end, one pan being ordinarily used for the weight and the other for the material to be weighed.

In such scales, the frame is supported on the base by knife edges with special supports, and the pans are similarly supported by the frame, and are connected by a check bar so that when the frame swings the pans will remain horizontal. Such scales employ knife edges resting on V-shaped supports in order to reduce friction, and it is necessary in manufacture to have the knife edges at exactly the same distance apart in order that the frame will balance accurately when there is no load on either pan. It has heretofore been customary to form the knife edges in the frame, or as a part of'it, and then to grind them until the accurate distances are obtained. As the knife edges on each side are ordinarily separate, it has been necessary not only to grind them so that the distance would be equal on each side, but also to have them line up accurately. The expense of doing this has been considerable, and it is the object of this invention to enable such scales to be constructed in large quantity without requiring so much expense in adjustment. This is accomplished by forming the knife edges of special material, which can be adjusted relatively to each other and then permanently fastened to the frame, without requiring any grinding. The knife edges rest in ordinary grooves in the supports as heretofore, but the supports are composed of thimbles or bushlngs which can be rotatably adjusted to correspond with the adjusted position of the knife edges. lThe knife edge supporting bushings have inserted therein the knife edge supports, the latter being of hard material, such as agate, or of hardened steel, and when properly adjusted can then be permanently fastened. These can be made in large quantities, and

the necessary holes in the frame can be drilled in jigs so that a scale embodying this invention can be made much more cheaply than has heretofore been possible. Also, in order to still further standardize this type of scale, the yokes which support the frame and the pans are alike,and interchangeable, this being rendered possible owing to (the standardlzation yof the knife edges and the knife edge supports above referred to. The lower ends of the pan yokes are extended downwardly into'the base and connected by the checkrod within the base, so that a scale of pleasing outward appearance and few moving parts is produced.

In the accompanying drawings, illustrating one embodiment of the invention,

Figure 1 is an elevation partly in section of a scale;

Fig. 2 is a plan view;

Fig. 3 is a section on the line 3 3 of Fig. 1;

Fig. 4 is a planvview of the check rod;

Fig. 5 is an end elevation of one of the knife edge supports;

Fig. 6 is a section on the line 6 6 of Fig. 5, and Figs. 7 and 8 show a form of clamp employed for the knife edges.

1 represents a hollow base having a seat 2, a central upright support 3 and upright hollow end stops 4 4. Mounted on the central support 3 is a yoke 5 having separated arms 6 6, which are transversely bored to receive the knife edge support 7. 8 is a set screw clamping the knife edge supports in proper position.

The beam frame 10 consists of a casting carrying at its center a knife edge bar 11 and at each end a knife edge bar 12 cooperating respectively with knife edge supports 7. 13 represents the pans, which are carried by yokes 14 similar to the yoke 6, except that theyokes 14' carry extension rods 15 which are horizontally connected by the check rod 16 within the base. The check rod 16 has lateral wings 17 at its middle portion which engage with depending stops 18 carried by the center support 3, so as to prevent longitudinal movement of the check rod. The ends of the check rod are connected by end pieces 19 to the vertical rods 15. Vertical rods 15 carry U-shaped clips 20, which are slotted to receive the ends 21 of the pieces 19. The pieces 19 are slipped on the ends of rods 16 until properly spared from the knife edges 23, and are then pinned to the rod 16 to maintain the proper dist-ance. At either side of the slots in the clips 20, the end pieces 19 have edges 22, which pivot on the clips 20. The clips 2O and end pieces 19 are connected to the rods 15 by screws 22 The stops 17 have similar edges 23 to engage the stop rods 1.8. By'this construction, the check rod is suspended from'the two lrods 15, so that it can swing parallel with the frame l0, but cannot move longitudinally nor laterally, and the connection herein described eliminates friction so that the sensltiveness of the scale is not affected.

As shown in F ig. 1, the knife edges 11 are continuous bars extending from one side of the yoke to the other, one-sideof the bar being of the `predetermined ,ij-shape without grinding, and the other side being made half round. The bar is seated in half round grooves made simultaneously in the frame so that with a straight bar, it is obvious the two edges will necessarily be in alinement when set in the frame. Qi are tl-shaped clips which clamp the knife edges to the frame, vthe clips being secured by screws r other fastening means. rllhe center knife edge 11 is first set with its edge pointing downward in practically a vertical direction7 and then one of the end knife edges 12 is similarly set, the'grooves having previously been made in the frame. rilhen the last knife edge can be oscillated slightly on the round base until-it is exactly equally distant from'the centerknife edgeli. Then the clip 2l is applied to permanently fasten the knife edge in its proper position. in practice, this is found to be a much simpler method of determiningthe distances of the rnife edges than previousmethods of grind ing, and after the clips' are onceset, there is no danger of the knifeedges either becoming out of parallelism or alinement, or distance, and the machining ofthe grooves at a single operation insures that thefknife edge on one side will line up with that on the other.. This l eliminates much grinding which has heretofore been done where the knife edges'were formed integral withlthe frame, and also thetiine required in grinding the outer-knife edges to be exactly in line with each other and equal distance from the center knifeedge.

The lknife edge supports 7 are shown in detail in Figs. 5 and 6, in which -is shownfan outer cylindrical bushing or thimble having a hole 26 in one end,"whichis covered by a glass plate 27 enabling the position of the knife edges on thesupports to be observed. rlhe knife edge support itself consists of a block 28 of steel, agate, or other suitable material, having a il-groove therein, and resiliently held in a spring 29, which is forced into the bushing 'i' so firmly as to be held against displacement. They bushings T be- .assembled andv properly calibrated, the

screws S and the screws l which hold the clips 24- can be cut Off, so that the scale cannot be tampered with, but this is not ordi- `nai-ily necessary.

From the foregoing description, it will be seen that the scale herein describedis composed of practically standardized parts, which can be cheaply made inquantity, and then can be assembled and accurately calibrated without the necessityV ofexpensive grinding, setting, or the like. Sofar as l am aware, it has not heretofore been proposed to employ in scales of this character, knife edges of bar material which `couldbe adjusted on the frame, or knifeedge supports capable of adjustment in Calibrating, and also capable of being renewedin `case of necessity. lt will also be seen that the knife edges and knifeedge supports herein described can be used on scales of various sizes without materiall increasinor the cost be made without departing from the scope of the appended claims.

What l claim is f 1. ln a scale, a frame, a bushing rotatably mounted therein, and a `knife edge support within said bushing.

2. In a scale, a cylindrical bushing, a resilient clip within said bushing, and a knife edge support of hard material adapted to be held by said clip.

3. A trip scale comprising a basehaving an' upright central supporting yoke, a cylindrical bushing carrying a knife edge support in each arm of said yoke, a frame carrying a transverse knife edge mounted on said yoke supports, a knife edge' at each end of said frame, a yoke carrying bushings and knife edge supports suspended from each of'said knife edges, a weight support carried by each ofsaid yokes, and a cheek rod within the base and connecting the lower ends of said yokes.

4. A scale comprising a base, a yo re centrally mounted thereon and carrying transversely disposed knifeV edge supports, a beam frame carrying a transverse knife edge bar, said support and saidbar being angularly adjustable relativelyv to 4each other.Y

5. ln a scale, a cylindrical bushing, a

knife edge support within said bushing, and a spring Clip holding the support in the bushing.

6. In a scale, a cylindrical bushing, a knife edge support within said bushing, u Spring clip holding the support in the bushing, and u glass closing one end of the bushing.

7. In a scale, a frame having a transverse cylindrical groove, a knife edge bar having 10 a cylindrical base resting in said groove, and a clip fastened to the frame and engaV ing said knife edge for retaining it in ajusted position.

In testimony whereof I aiix In si nature. 15

FREDERICK M. SIYEWNS. 

